PEO基Li^(+)-g-C_(3)N_(4)复合固态电解质的制备及其电化学性能

Synthesis and performances of Li^(+) modified g-C_(3)N_(4) for PEO-based composite solid electrolyte

利用g-C_(3)N_(4)表面丰富的官能团进行锂化,得到锂化氮化碳(L-g-C_(3)N_(4))材料,并以双三氟甲基磺酰亚胺锂(LiTFSI)为锂盐,聚环氧乙烯(PEO)为聚合物基体,采用流延-热压法制备Li^(+)-g-C_(3)N_(4)复合固态电解质。借助透射电子显微镜(TEM)、X射线衍射仪(XRD)、红外光谱仪(FT-IR)、差示扫描量热法(DSC)、线性循环伏安(LSV)、直流极化曲线、交流阻抗谱以及充放电测试等手段对复合固态电解质进行表征和测试。对比分析相同质量分数g-C_(3)N_(4)复合固态电解质与L-g-C_(3)N_(4)复合固态电解质的电化学性能,同时对不同L-g-C_(3)N_(4)含量的复合固态电解质的电化学性能进行研究。结果表明,添加质量分数为10%L-g-C_(3)N_(4)的复合固态电解质在60℃时的离子电导率为3.95×10^(-4) S/cm,锂离子迁移数为0.639,电化学窗口为4.5 V以上。以复合固态电解质组装Li/LiFePO_(4)全固态电池,在60℃以0.5 C充放电,电池的首次放电比容量为163.76 mAh/g,循环80次后容量仍有160.10 mAh/g,容量保持率为97.8%。

The rich functional groups on the surface of g-C_(3)N_(4) were used for lithiation to acquire lithiated g-C_(3)N_(4)(L-g-C_(3)N_(4)).Bistrifluoromethane sulfonimide lithium salt as the lithium salt and polyvinyl epoxide as the polymer matrix was used to prepare L-g-C_(3)N_(4) composite solid electrolytes using the casting-hot-pressing method.Transmission electron microscopy,X-ray diffractometer,infrared spectrometer,differential scanning calorimetry,linear cyclic voltammetry,DC polarization curve,electrochemical impedance spectroscopy and charge discharge tests were used to characterize and test the composite solid electrolytes.g-C_(3)N_(4) composite solid electrolyte and L-g-C_(3)N_(4) composite solid electrolyte were compared and their electrochemical properties were evaluated.Simultaneously,composite solid electrolytes with different L-g-C_(3)N_(4) content levels were also studied.The results revealed that the composite solid electrolyte's ionic conductivity is 3.95×10^(-4) S/cm,the Li^(+)migration number is 0.639,and the electrochemical window is higher than 4.5 V.The Li/LiFePO4 all-solid-state batteries were gathered with composite solid electrolytes.The battery's initial specific discharge capacity was 163.76 mAh/g for the first discharge when charged-discharged with 0.5 C in 2.5-4.0 V at 60℃.After 80 cycles,the capacity was still 160.10 mAh/g,and the capacity retention rate was 97.8%.